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Author Topic: Designing with one-stack unstiffened and sandwich concepts  (Read 6932 times)

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Designing with one-stack unstiffened and sandwich concepts
« on: November 05, 2008, 04:15:00 PM »
1)In the panel analysis in HyperSizer using unstiffened plate Family, I assume "one stack unstiffened", "two stacks unstiffened", "three stack unstiffened" don't make any difference in the case of having isotropic materials. But with composite materials, using the above mentioned options is helpful since we can create one lay up once and have it repeated some more time. Is this correct?

2) I was hoping to be able to use sandwich panel concept, with the upper and lower face sheets linked and no core (essentially by assigning no material to the core). But the HyperSizer complains. It seems the only way that you can get that running is through choosing both "sandwich concept" and "one stack unstiffened". But it is not clear to me why should it be considered “one stack” and why if I don't use that (i.e., use Sandwich panel concept only with linked upper and lower face sheets) I am not able to run the analysis.

3) This question is about the set value of “Required margin of safety” in “Failure” section.
I guess the way it works is that if you are getting a higher margin of safety compared to what "Required margin of safety" is set at then changing "Required margin of safety" won’t change your analysis results. But, if over the range of variables that you have, HyperSizer gives a lower margin of safety than what is required it will go ahead and chooses the combination of dimensions, concepts, materials,… to increase the MS to get as close as possible to the value set for "required limit margin of safety ". Right?


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Re: Designing with one-stack unstiffened and sandwich concepts
« Reply #1 on: November 05, 2008, 04:15:38 PM »
1. You could use the two or three stack in the way you describe. For metallics, you could use the two or three stack to model a bi-metallic strip with two different metallics and then say apply thermal loads to see bending of a bi-metallic strip.

2. For a honeycomb sandwich or foam sandwich you must specify a core material. If you want a "void" for a core, you could perhaps create a foam material with very low properties and close to zero density to approximate this. What is happening if you select honeycomb sandwich and one-stack unstiffened, but do not specify a core material, then the software is not giving you a sandwich, but rather just giving you an unstiffened plate. The link facesheets options will only work for sandwiches.

After sizing, go to the Failure tab to see what the software chose as an optimum concept.

3. That is essentially correct. See the following: